wifi(tests): Unit tests for iface event cb's

Few class refactors to help with unit tests for ag/7567226.

Bug: 132943959
Test: ./hardware/interfaces/wifi/1.3/default/tests/runtests.sh
Change-Id: I62909f3f94899bc1593824684b93d29f44954eae
diff --git a/wifi/1.3/default/wifi_iface_util.h b/wifi/1.3/default/wifi_iface_util.h
index 325fbe8..98073e0 100644
--- a/wifi/1.3/default/wifi_iface_util.h
+++ b/wifi/1.3/default/wifi_iface_util.h
@@ -40,7 +40,7 @@
  */
 class WifiIfaceUtil {
    public:
-    WifiIfaceUtil();
+    WifiIfaceUtil(const std::weak_ptr<wifi_system::InterfaceTool> iface_tool);
     virtual ~WifiIfaceUtil() = default;
 
     virtual std::array<uint8_t, 6> getFactoryMacAddress(
@@ -60,7 +60,7 @@
    private:
     std::array<uint8_t, 6> createRandomMacAddress();
 
-    wifi_system::InterfaceTool iface_tool_;
+    std::weak_ptr<wifi_system::InterfaceTool> iface_tool_;
     std::unique_ptr<std::array<uint8_t, 6>> random_mac_address_;
     std::map<std::string, IfaceEventHandlers> event_handlers_map_;
 };